I randomly googled & opened a 3d printer product, which specified that it supports "Windows XP, Vista, Windows 7, OSX 10.7 beta" (ironically, no Win8)
So, as usual, it means nothing more than empty marketing hype. Windows Vista's "support" for cd/dvd burning meant nothing either. It's not like you couldn't do it before they "supported" it.
It'll mean even less for the common user who'll never use a 3d-printer, and the professional who'll probably never use Win8. (I see large rich client companies being quick to adopt the latest software where managers aren't tech-savvy, but the specialist contractors who sometimes visit to do some consulting work or project are usually still working on Win2000 & Excel with their own modified engineering or finance spreadsheets)